Milky Way and globular clusters

 Some photos from Tuesday (08 Sep) and Thursday (10 Sep).  The Milky Way image was obtained with a Sony A7iii camera and a Laowa 15mm f/2 lens.  The other images were obtained with an Apertura 60mmED f/6 refractor and an Olympus E-M5iii camera.

Milky Way and air glow over Bristol Head.  120 s, ISO 1600, Sparkle-6 filter.

 Globular clusters exist in the galactic halo of the Milky Way and are some of the oldest objects in our galaxy.  They are spherical, gravitationally stable clusters of stars with hundreds of thousands or even millions of members.

The globular-cluster images are 1-deg square field-of-view. 

Globular cluster M4 in Scorpius

Globular cluster M5 in Serpens

Globular cluster M10 in Ophiuchus

Globular cluster M12 in Ophiuchus

Globular cluster M13 in Hercules

Globular cluster M22 in Sagittarius

A daytime partial occultation of Jupiter

 Some stars and planets are bright enough to be seen during broad daylight, if you know where and how to look.  A good example occurred today when the moon passed in front of the planet Jupiter (an occultation) in the middle of the day.  From my location here in Creede, the occultation was partial, meaning the Moon obscured only part of Jupiter's disc.  Maximum occultation occurred at about 1:14pm MDT, at which time 29% of Jupiter's diameter was obscured.

The following images were obtained with an Apertura 60mmED f/6 refractor.  Clouds nearly obscured the event, but a hole opened up just as the Moon was passing Jupiter.  I missed the beginning, but managed to see the exit and very nearly the maximum occultation.

Jupiter (left) about 2 hr before occultation

 

The Moon and Jupiter about 1 hr before occultation

 

Jupiter partially obscured.  About 1 min past maximum.

About 13 minutes past maximum

Saturday Milky Way

 The sky brightness was 21.44 mpsas.  There were some wispy clouds along the southwest horizon.  The camera was a Sony A7iii with a Laowa 15mm f/2 rectilinear lens and a Hoya Sparkle-6 filter.  Exposures were 58 s at ISO 1600.

Vega (top center) over the Bristol Head ridgeline

 

The Milky Way and other sights

 Another clear evening, nicely but not impressively dark with a measured brightness of 21.4 mpsas. After capturing the Milky Way with a Laowa 7.5mm f/2 rectilinear lens on an OM-5ii camera, I photographed some deep-sky objects using a Rokinon 135mm f/2 Nikon-mount lens adapted to a Sony A7iii camera.

Milky Way rising through southern airglow. no filter

digital 3x3 median filter

 The dwarf planet Pluto is currently at magnitude 14.5 east of the Milky Way in the constellation Capricornus .  I was able to capture it with a 2-min exposure at ISO 100.  This was an inadvertent test of the ISO invariance of the Sony A7iii.  The exposure was pushed 4 stops in post-processing.

Pluto (circled). 2x enlargement. 

 Farther east, the asteroid (9) Metis is making a close pass (1.9°) to the Helix Nebula (NGC 7293).  Metis is the 35th largest asteroid with dimensions on the order of 200 km.  It was discovered in 1848.

(9) Metis (circled) and the Helix Nebula (LR) in Aquarius. 30 s, ISO 1600

 The Andromeda Galaxy, M31, is now becoming well positioned for viewing in the late evening.

M31. 62 s, ISO 1600

 

M31, 3x3 median filter

The Double Cluster in Perseus. 30 s, ISO 1600

Caroline's Rose (NGC 7789), an open cluster in Cassiopeia

Venus, Saturn, Neptune

With the Moon gone, Venus is once again the brightest object in the evening sky, shining at magnitude -4.5.  It is now a fat crescent and will get slimmer as it approaches peak brightness in a couple weeks.  While setting behind the Bristol Head ridgeline, it is bright enough to illuminate the trees in front of it.

The following images were obtained with a Sightron infini D50 refractor and a 1.5x MDB (effective focal length 905 mm).

Venus setting behind Bristol Head

illuminated trees

crescent Venus, 1/1000 s, ISO 1600

 It is hard to get a sharp image of the planet with just a single exposure like this because of atmospheric effects, especially when it is so low in elevation.  The standard practice is to take tens, hundreds, or even thousands of images (in video format), then select and stack the sharpest fraction of video frames to produce a final image.  

  Astronomical twilight ends shortly after 9 pm (MDT) and the moonless sky is dark enough again to photograph constellations.  The following images were obtained with a Sigma 30mm f/1.4 lens.  Sky brightness was a modest 21.38 mpsas.

Cassiopeia and the Double Cluster (lower middle). Softon filter.

The Andromeda Galaxy (M31) and the Triangulum Galaxy (M33). Softon.

M31 (top) and M33 (bottom)

 The image above was obtained with no optical filter, but a low-pass digital filter (3x3 median) was applied in post-processing.  M31, the great Andromeda Galaxy, is the largest member of our Local Group of galaxies.  M33, the Triangulum Galaxy (also sometimes called the Pinwheel Galaxy), is the third largest member after our own Milky Way Galaxy.  It is about 2/3 the size of our galaxy.

M33 is right on the verge of naked-eye visibility from an exceptionally dark site with good eyes. At a distance of 2.9 million light-years (Mly), it is likely the farthest object that can be seen without optical aid.

 The planet Saturn is currently on the boundary line between the constellations Pisces and Cetus.  It is rising above the ridgeline of Snowshoe mountain in the late evening.

Saturn (LL), Neptune (circled) and the Circlet of Pisces (upper right)

 The Circlet of Pisces is an asterism formed by a ring of seven stars in the constellation Pisces.  The planet Neptune currently shines at magnitude 7.8.  This puts it within the range of binoculars when aided by a good star chart.

First look at the September Milky Way

 After a long string of cloudy or moonlit nights, there was finally a clear sky last night (01 Sep) with about 40 min of darkness between the end of astronomical twilight at 9:08 pm and the rise of the 19.9-day waning gibbous Moon.  The measured sky brightness was 21.4 mpsas, which is very good but not exceptional (for this area),

The following images were obtained with a Panasonic Leica 12mm f/1.4 lens and an OM-5ii camera.

 

Sparkle-6 filter

 

low-pass digital filter

The image above was obtained with no physical filter on the lens, but a digital low-pass filter (3x3 median) was applied in post-processing.  This suppresses the myriad faint stars and lets the dark dust clouds of the Milky Way stand out more clearly.

 

Arcturus in the airglow above Bristol Head. Softon filter

View to the north: Big Dipper and Little Dipper.  Softon filter

More Sturgeon Moon

 A few more pictures from the mostly-clouded-out lunar eclipse on Thursday.  

I just discovered that Blogger has somehow changed the way files are stored, so downloading images with the original filename and size no longer works.  This seems to affect anything posted after 31 July.  So this post is an experiment, linking images to Google Photos instead of direct uploads. Sigh.

 

It seems to work, but what an ugly process